Added a CMake option for building as an AppImage and enabled it in the AppImage build scripts.

CMakeLists.txt

@@ -34,6 +34,7 @@ list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/CMake/Utils
 # Define the options.
 option(GL "Set to ON if targeting Desktop OpenGL 3.3" ${GL})
 option(GLES "Set to ON if targeting OpenGL ES 3.0" ${GLES})
+option(APPIMAGE_BUILD "Set to ON when building as an AppImage" ${APPIMAGE_BUILD})
 option(FLATPAK_BUILD "Set to ON when building as a Flatpak" ${FLATPAK_BUILD})
 option(STEAM_DECK "Set to ON to enable Valve Steam Deck specific build" ${STEAM_DECK})
 option(RPI "Set to ON to enable Raspberry Pi specific build" ${RPI})
@@ -284,8 +285,22 @@ if(GLES)
     add_compile_definitions(USE_OPENGLES)
 endif()
 
-# When building as a Flatpak, all launch commands will be prefixed by "flatpak-spawn --host".
+if (APPIMAGE_BUILD AND FLATPAK_BUILD)
+    message(FATAL_ERROR "-- APPIMAGE_BUILD and FLATPAK_BUILD can't be combined")
+endif()
+
+if(APPIMAGE_BUILD)
+    if(NOT CMAKE_SYSTEM_NAME MATCHES Linux)
+        message(FATAL_ERROR "-- APPIMAGE_BUILD can only be used when building on Linux")
+    endif()
+    add_compile_definitions(APPIMAGE_BUILD)
+    message("-- Building as an AppImage")
+endif()
+
 if(FLATPAK_BUILD)
+    if(NOT CMAKE_SYSTEM_NAME MATCHES Linux)
+        message(FATAL_ERROR "-- FLATPAK_BUILD can only be used when building on Linux")
+    endif()
     add_compile_definitions(FLATPAK_BUILD)
     message("-- Building as a Flatpak")
 endif()

tools/create_AppImage.sh

@@ -38,7 +38,7 @@ rm -rf ./AppDir
 mkdir AppDir
 
 rm -f CMakeCache.txt
-cmake -DBUNDLED_CERTS=on .
+cmake -DAPPIMAGE_BUILD=on -DBUNDLED_CERTS=on .
 make clean
 make -j8
 make install DESTDIR=AppDir

tools/create_AppImage_SteamDeck.sh

@@ -34,7 +34,7 @@ rm -rf ./AppDir
 mkdir AppDir
 
 rm -f CMakeCache.txt
-cmake -DSTEAM_DECK=on .
+cmake -DAPPIMAGE_BUILD=on -DSTEAM_DECK=on .
 make clean
 make -j8
 make install DESTDIR=AppDir